Process and apparatus for fractional condensation



5 Sheets-Sheet l J. E. BELL Filed March 25, 1922 PROCESS ANDAPPARATUS FOR FRAGTIONAL CONDENSATION Feb ' J. E. BELL I PROCESS AND APPARATUS FOR FRACTIONAL CONDENSATION 5 Shee eet 2 Jaz/az 07* Filed March 25, 1922 J. E. BELL PROCESS AND APPARATUS FOR FRACTIONAL CONDENSATION Feb. 16 1926. 1,573,129

Filed March 23, 1922 5 Sheets-Sheet 5 fzdezzzw? Feb. 16 1926. 1,573,129

J. E. BELL PROCESS AND APPARATUS FOR FRACTIONAL CONDENSATION Filed March 25, 1922 5 Sheets-Sheet A Feb. 16 ,1926. 1,573,129

. J. E. BELL PROCESS AND APPARATUS FOR FRACTIONAL CONDENSATION Filed March 25, 1922 BSheets-Sheet 5 o o o o o o 0 o o o 0 o o 0 o o 0 0 0 0 0 0 0 0 0 o o o o o o B e o o o o o o o o o o o 0 0 L0 o o o o o o o o V m w w w mw w w e w w w w w o o o o o o o o ooo o o Patented Feb. 16, 1926.

UNITED STATES P'gATENT OFFICE.

JOHN E. BELL, OF BROOKLYN, NEW YORK, AS SIGNOR IO SINCLAIR REFINING COM- PAN Y, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

PROCESS AND APPARATUS FOR FRA CTIONAL COITDENSATION.

Application filed March 23, 1922. Serial No. 545,951.

To all whom it may concern:

Be it known that I, JOHN E. BELL, a citi-' zen of the United States, residing at Brooklyn, county of Kings, State of New York, have invented certain new and useful Improvements in Processes and Apparatus for Fractional Condensation, of which the following is a specification.

Crude petroleum has heretofore been separated into the various fractions thereof corresponding to the desired commercial product and residues by fractional distillation. In this process the oil is slowly heated through the range of temperatures in which the desired distillates are given off, the vapors being condensed as they issue from the still. Cuts or divisions are made at successively higher temperatures, the points at which the cuts are made being determined by the gravities of the components which are to be embraced in the respective fractions or cuts, as they are commonly called, which after refinement constitute the commercial products. In practice, however, it has been found possible only to approximately separate the compounds into fractions according to their gravities, some of the compounds of heavier gravities being carried over withthose of lighter gravities, and some of the lighter oils remaining after the temperature has been raised above their boiling point and so forming a portion of the cut or fraction. intended to contain only heavier oils. It has therefore been necessary in order to secure a sufliciently sharp division between the cuts and to prevent the respective commercial products from containing oils of lighter or heavier gravities than they are designed or intended to con- .tain to re-run or rc-distill the roduct of the first distillation. Such res-distillation, however, is expensive, requiring costly additional apparatus, consuming'large quantities of fuel, and requiring the attention of additional operatives.

It is the purpose of the present invention to avoid this additional expense by effecting the separation of the components of the oil into their respective groups or cuts with sutlicient thoroughness in a single operation for commercial purposes. It is known that the sharpness of cut in a condenser depends .upon the temperature difference between the vapors condensed and the condensing surface or medium, the nearer the latter approaches in temperature the vapors to be condensed the sharper being the out. On the other hand, the less the temperature difference the less effective the condenser, or otherwise put, the larger must be the contact surface to secure the same amount of condensation. In practice, therefore, compromise must be made between etliciency of operation and sharpness of cut and it becomes important to so control the temperature of the condenser that the essential degree of sharpness of cut is attained without too much sacrifice of efficiency. One of the objects of the present invention is to provide a process and apparatus by which it is possible to secure the desired number of cuts while causing each cut to be condensed at a temperature slightly below, but sufliciently near that of the vapors being condensed to secure the required degree of sharpness. For this purpose I carry on the condensation process by means of a cooling medium which is continuously circulated, and I control the temperature of the medium by replacing a portion of it with fresh cooling medium from time to time during such circulation. The cooling medium I prefer to use is air and in the condensing apparatus this air is circulated through pipes which constitute .the condensing surfaces. During such circulation more or less of the air in the condenser is replaced by cooler air from the atmosphere so that the desired temperature gradient may be secured throughout the condenser. The vapors coming from the still are brought into contact with hot but successivelycooler surfaces, so that the components thereof are condensed in the order of their gravities, or substantially so, the condensates as formed being either drawn oil in separate cuts or first submitted to more or less re-distillation in thecondenser by contact with the vapors of higher temperature, before leaving the apparatus. For this latter purpose the apparatus is arranged in the form of a series of chambers "through which the vapors to be condensed are successively introduced. Condensation occurs in each of these chambers and the condensate so formed is introduced into .the chamber prior in series and mingled with the condensate formed from the vapors in that chamber. In such mingling, however, the condensate first mentioned is brought into direct contact with the vapors flowing through that chamber, and these vapors bring about the redistillation referred to.

In the accompanying drawing and following specification I haye disclosed two embodiments of apparatus embodying the invention and in which the new process may be carried on; it is to be understood, however, that the specific disclosures are for the purpose of exemplification only and that the scope ofthe invention is defined in the following claims in which I have endeavored to distinguish it from the prior art so far as known to me without, however, relinquishing or abandoning any portion or feature thereof.

The simpler embodiment of the apparatus is shown in Figs. 1 to-3 of the drawing and the preferred form in Figs. 4 to 6 thereof. Fig. 1 is a plan of the simpler embodiment; Fig. 2 a vertical section on line 22 of Fig. 1 on an enlarged scale; Fig. 3 a vertical section on a similar scale on line 33 of Fig. 1 looking in the direction of the arrows, parts being shown in elevation; Fig. 4 a plan of the preferred form of the apparatus; Fig. 5 a vertical longitudinal section thereof, and Fig. 6 a vertical section on line 66 of Fig. 5. Each part is identified by the same reference character wherever it occurs in the several views.

Referring first to the simpler form of the apparatus shown in Figs. 1, 2 and 3, the condenser will be seen to comprise a number of condensing elements a, 0?, etc., which are identical in construction and operation except in respects hereinafter pointed out, and therefore a description of one will serve for all. A cylinder 7 is fitted with heads 8, 9 which may be held in place by bolts 10. The heads 8, 9 throughout corresponding rectangular areas are bored and connected by tubes 11 for the passage of air. Air ducts 11 cover the perforated areas ofthe respective heads and communicate with said tubes to provide for the circulation of air through the tubes of all the elements in series. These elements a and a a and a, a and a are connected on one side of the series by the Ushaped air conduits 12, 13 and 14, and elements (1 and a a and a are connected on the other side of the series by similar air conduits 15 and 16. An air pump 17 driven by motor 1.8, circulates air through the series of condenser elements, the intake side of the pump being connected by conduits 19- 4,0 to the element a and the exhaust pipe to ei ement a by conduit 21. I

In order to regulate the temperature of the air and reduce it to that necessary to maintain the desired temperatures of the condensing surfaces I may provide for the replacement of a portion of the air by fresh or cooler air. For this purpose an air outlet 22 and an-air inlet 23 are provided, con-' trolled respectively by dampers 24, 25. The circulation may be regulated by damper 26, all of said dampers being provided as usual with means for holding them in adjusted position.

The vapors as they come from the still or from another condenser by which their heavier components have been removed, are circulated through the series of condenser elements preferably-in a direction the reverse of that in which the air is circulated, so that the air in its cooler state acts upon the vapors after their temperature has been lowered. For this purpose elements a and a a and a a and a are connected near their ends on one side of'the series by U- tubes 27, 28, 29, respectively, and elements a and a and a and a near their opposite ends have similar U-tubes 30, 31. Element (1 is provided with an inlet 32 which may be connected to a still or another condenser, as previously explained, and element a has an outlet 33 which may lead to a further condenser or storage receptacle for vapors or gases or both. Thus the vapors pass through the condenser elements in succession and in contact with the air-conveying tubes therein.

Preferably in order to secure more thorough circulation of the vapors about the tubes the group of tubes in each cylinder is boxed in on opposite sides by plates 34, 35, and each element is provided with a baffle 36 to compel the gases to traverse the group of air pipes twice, and bafiies 37, 38 to spread the vapors in the chamber.

Each condenser element has a draw-off 39 for condensates, so that a separate cut can be taken off from each element.

Thermometer Wells or mountings are provided in each air conduit as at 40 and in each vapor conduit as at41, whereby tem- K'late through the condensing elements of the series, consequently there is condensate formed in each element, the heaviest vapors condensing and forming a cut in the first element, the next heaviest in the second element, and so on, and each cut may be drawn ofi from the element in which it is formed and either used unmixed, or combined with suitable proportions of other cuts to form a commercial product. The'air may be circulated through the apparatus without admixture of cooler air and so heated to a temperature very little below that of the vapors, in which case the temperatures of the condensing surfaces will be correspondingly high. and the cuts shar ly defined. In order to secure greater .con ensation, however, I ordinarily prefer to mix more or less cooler air continuously with that circulated through the condenser, this being accomplished by so regulating the valves 23,24 that there is continuous exhaust of'heated' air and influx of cooler air,' the amount of -replaccment being determined by observing the readings of the thermometers in the various wells'and adjusting the valves accordinglyf The process as carried out by the apparatus shown in Figs. 4, 5 and 6 is in the main similar to that carried on by the apparatus already described, involving the circulation of vapors in contact with air cooled surfaces maintained at successively diminishing temperatures by circulation of air, the temperature of whichis controlled'by admixture of cooler air therewith. In the apparatus to be now described a single continuous body 45 replaces the condenser elements of the previously described form and is so partitioned by baifie plates as to provide for a series of chambers or compartments through. which the vapors pass successively and from which the desired cuts may be separately removed.

As best seen in Fig. 5 the condenser body is provided at its ends with end walls 45, 4-5", in which are inserted headers 46, 47 connected by tubes 48 extending longitudinally of the body and through which air is circulated as will presently appear. v

A vapor inlet 49 in the top of the condenser body near one end thereof is connected to the vapor line of the still or to a higher temperature condenser and a vapor outlet 50 near the other end to a cooler condenser in which the uncondensed vapors may be further treated. The vapor space of the condenser is divided by vertical bafiles 51, 52,-bafiles 51 extending from the top of the condenser nearly to the bottom thereof and baffles 52 from the bottom nearly to the top, so that the vapors entering by the inletare forced to a circuitous or zigzag course, traversing the battery of air cooled pipes back and forth many times before reaching the outlet. It will be observed that the passages for the vapors between the baflics are much larger near the vapor inlet, diminishing toward the outlet asthe volume of vapors is decreased by condensatioih The bottom sections 53, 54, 55, 56 form pockets with baflies 52 for the reception of separate bodies or cuts of condensate formed inlthe respective vapor spaces between said walls and bafiies immediately above. Preferably the bottom is stepped, the bottom sec tions being at successively higher levels from the inlet to the outlet end of the condenser for a purpose which will appear. Each division or compartment of the condenser is provided a short distance above its bottom, with a header 57 constituting a false bottom in which are secured numerous upwardl extending short lengths of tube 58. A rain pipe 59 is also secured in an opening in each header or false bottom except that at the inlet end of the condenser, and communicates with the space between the bottom and header of the compartment to the right. As the vapors are cooled in their passage through the condenser, the heaviest group or cut is condensed in the first or extreme right hand compartment (as seen in Fig. 5), the nextheaviest in the second com artment, and soon, and the condensates col ect in the respective lower ends of said compartments, above the false bottoms between and around the tube sections mounted therein. The condensate collecting on any false bot-tom (except the first) passes from the overflow pipes 59 to the space below the false bottom in the preceding compartment/whence the condensate passes upwardly through the tubes 58' and overflows or cascades from the upper ends of these tubes into the space above the false bottom where it mixes with the condensate surrounding these tubes. In. thus overflowing the mixed condensate is subjected in a series of thin films to the hotter vapors circulating about the tube sections and over the ends thereof and the more volatile components, particularly those which have refluxed from the. adjacent somewhat cooler compartments arerevaporized and intermingled with the passing vapors. At the same time the exposure of the passing vapors to the films of condensate above and about the tubes 58 condenses more or less of the heavier components'th'ercof. It will be noted that thebaiile 51 extends down closely to the top of the tubes 58, forcing the vapors to pursue a path about such tubes, thus assuring intimate contact between the condensate films and the vapors, and furthermore, that the descent of the vapors in a vertical path on the one side of each baflle 51 followedby the sharp reversal of flow on the other side thereof tends to de osit any drops or particules of liquid con ensed in the lower end of the compartment.

Referringmore particularly to Figs. 4 and 5, the headers 46, 47 are seen to be surrounded or covered by hood-s 71, 72 respectivel Hood 72 is connected by a reduced neck 73 with a fan chamber 74 containing a fan 75, and the latter is driven by a motor 76 of any suitable or approved type. Hood 71 and fan chamber 71 are connected by an air conduit 77 .(see Figs. 4 and 6) so that air may be continuously circulated by fan 75 through a closed circuit through conduit 77, hood 71, condenser tubes 48, hood 72, neck 73 and fan cham or 7 1. i

In order to properly control the temperature of the condensing surfaces formed'by said tubes I provide for the replacement of any desired portion of the hot air in the circuit b cooler air. For this purpose hood 72 is ormed with an escape flue 79 having a butterfly valve or damper 80 therein, and neck 73 is open to a collar 81 slot-ted at suitable intervals as at 82 and surrounded by a rotary slotted sleeve 83, the slots of which may be caused to completely or partially register with the slots in the collarso' as' to provide inlets for cooler air. Obviously, by adjusting the' sleeve 83 and valve 80 the amount of air replaced per unit of time may be closely regulated and thus thetemperatureof the entire body of air in the apparatus and of the condensing tubes accurately controlled. 'If very little temperature differential between the condensing surfaces and thevapors is desired it has been found that sleeve 83 may be so positioned as to close the apertures 82 and butterfly valve 80 closed, when the temperature of the air will be reduced only by such fresh air as enters crevices in the construction, and by such cooling as is effected in the conduit T17. because of the exposure of the latter to the atmosphere.

In order to closely observe the temperature thermometer wells 8,6 are provided at suitable points in the condenser. Instead of introducing the vapors at inlet 49 all or a portion thereof may be introduced at the inlet 89 arranged, as shown in Fig. 5, midway of the condenser. In some instances it may be desirable to introduce at the inlet 49, certain vapors and at inlet 89 other vapors which lack some of the heavier constituents of the vapors introduced at inlet 49.

It will be seen that in the process as carried on by the apparatus just described. the vapors to be condensed flow successively through a series of chambers the temperatures of which gradually diminish. The cooling medium, air, flows through the condensing apparatus in a direction opposite to the direction of flow of the vaporsto be treated and the temperature of this cooling medium is continuously regulated by replacing a portion of it with fresh air during its circulation. Cuts may be separately col leeted from each of the chambers or the condenser may be used for producing a single cut, in which event the comlensate may be withdrawn from the bottom of the first condensing chamber which has received the condensates from the chambers later in series. Where a single cut is so produced,

the condensates formed in each chamber (except the first) are then exposed to suecessive redistillation by direct contact with the vapors flowing in the chambers prior in series, and this-permits of a much greater sharpness of cut by reason of the redistillation and condensation of the cuts. The temperature of the cooling medium in any chamber is only slightly below that of the vapors passing through that chamber and this permits the condensation to occur under those conditions which are most conducive to sharpness of cut.

I claim:

1. A process of the class described, which comprises passing the vapors to. be condensed into heat exchange relationship with a cool- .ing medium moving through a closed circuit, and regulating the temperature of the medium by replacing a portion thereof with fresh cooling medium.

2. A process of the class described which comprises passing the vapors to be condensed into heat exchange relationship with a cooling medium. moving through a closed circuit, removing heat from said medium during such movement and while it is out of such relationship, and regulating the temperature of the medium by replacing-a portion'thereof with fresh cooling medium.

A process of the class described which comprises passing the vapors to be con-- densed through a series of compartments in heat exchange relationship with a cooling medium moving through a closed circuit, collecting the condensate formed in each compartment and exposing the condensate formed in each compartment (except the first) to the vapors flowing through a compartment prior in the series.

4. A process of the class described which comprises passing the vapors to be condensed through a series of compartments in heat exchange relationshipwith a cooling medium flowing through a closed circuit. collecting the condensate formed in each compartment and successively exposing the condensate formed in each compartment (except the first) to the Vapors flowing through the compartments prior in the series. i

5. A process of the class described which comprises passing the vapors to he condensed through a series of compartments of diminishing size in-heat exchange relationship with a cooling medium moving through a closed circuit, and regulating the temperature of the medium by replacing a portion thereof with fresh cooling medium.

6. A process of the class described which comprises passing the vapors to be conposing the condensate formed in each com partment (except the first) to the vapors flowing through a compartment prior in the series, and mingling this condensate with the condensate formed in that prior compartment.

8. A process of the class described which comprises passing the vapors to be condensed through a series of compartments in heat exchange relationship with a cooling medium moving in a closed circuit through all the compartments, collecting the condensate formed in each compartment and introducing it into a compartment prior in the series. while exposing it to the vapors flowing throu h that compartment, mingling the c ndensate with the condensate formed in tie'prior compartment and mingling the vapors given off by the condensate first mentioi'ned during such exposure with the vapors flowing through the compartment.

9. A process of the class described which comprises passing the vapors to be condensed through a series of compartments of diminishing size in heat exchange relationship with a cooling medium flowing in a closed circuit through all the compartments, causing the condensate formed in each'compartment (except the first) to overflow into a compartment prior in series in direct contact with the vapors passing therethrough,

and regulating the temperature of the me-' dium during its movement by replaclng a portion thereof with fresh cooling medium.

10. In an apparatus of the class described, a condensing chamber having a vapor inlet, coolingtubes extending through said chamher and constituting condensing surfaces, a closed circuit including said tubes, means for circulating the cooling fluid through said circuit, and means regulating the temperature .of the medium in said circuit by replacing a'portion thereof with fresh cooling medium.

11. In an apparatus of the class described, a condensing chamber having a vapor inlet, tubes extending therethrough, the surfaces of which constitute condensing surfaces, a conduit connected at its respective ends to the opposite ends of the tubes, air forcing means in the conduit, means for admitting fresh air to the conduit. and means for permitting the escape of air therefrom.

12. In an apparatus of the class described, a condensing chamber, a vapor inlet at one end thereof and a vapor outlet at the other end thereof, the bottom of the chamber comprising a series of sections each successively raised with respect to the adjacent section nearer the vapor inlet, bafile extending upward from said bottom intermediate said sections and forming pockets therewith, and means for conducting condensate from each bottom section except the lowest one to-the next lower section.

13. In an apparatus-of the class described, a condensing chamber, a vaporinlet at one end thereof and'a vapor outlet at the other end thereof, the bottom of the chamber comprising a series of sections each successlvely raised with respect to the adjacent section nearer the vapor inlet, baffles extending upward from said bottom intermediate said sections and forming pockets therewith, horizontal headers in each of said pockets above and spaced from the bottom section thereof, tube sections extending through said headers and abbve the same, and pipes, connecting the space above said-header of each section except the lowest one with the space below the header of the adjacent section toward the vapor inlet. y

14. In an apparatus of the class described, a condensing chamber, a vapor inlet at one end thereof and a vapor outlet at the other .end thereof, the bottom of the chamber comprising a series of sections each successively raised with respect to the adjacent section nearer the vapor inlet, bafiles extending upward from said bottom intermediate said sections and forming pockets therewith, bat: fl'es intermediate the first-mentioned baflies and extending from the top of the chamber nearly to the bottom thereof, headers arranged in each pocket above and spaced from the bottom of the pockets, overflow tubes in each header extendingabove the same, and a connection from the space above each header except the lowermost to the space beneath the header in the adjacent put-set toward the vapor inlet.

15. In an apparatus of the class described, a condensing chamber, a vapor inlet atone end thereof and a vapor outlet at the other end thereof, a series of transverse baflies extending upward from the bottom of said chamber and forming pockets therein for the reception of condensate, cooling means extending through said chamber, an ofl'take from each pocket-and means for conducting the condensate from each pocket except that nearest the vapor intake and injecting it into the adjacent vapor pocket nearer the vapor intake.

16. In an apparatus of the class described, a condensing chamber having a vapor inlet at one end thereof and a vapor outlet at theother end thereof, cooling means'extending through said chamber, partitions dividing the lower portion of the chamber into a lon.

gitudinal series of pockets, a false bottom in each ofsaid-gpockets forming a chamber beneath the same,a pipe section extending opening above each false bottom, except that nearest the vapor inlet 'and communicating with the space beneath the adjacent false bottom nearer the vapor inlet.

JOHN E. BELL. 

